The traditional metal padlocks which is commonly used on many families have many shortcomings on padlocks. One of them is if house-owner forgot to take the keys, then they have to ask the locksmith to open or break their lock by themselves. Moreover, the metal padlocks have a low security because they can be easily unlocked by people who familiar with mechanics. As the traditional lock raised a security issue, more and more locks company realized that it is necessary to provide safer door lock such as smart lock which use facial and fingerprint recognition to provide a much convenient and safe way to lock the door.

Lock manufacturers started to use Metal Injection Molding（MIM）technology to produce their metal parts, especially those parts with prety complex structure, high precision, high strengh and very smooth surface finish demands, such as the transmission gears used on the door locks clutches, SS17-4PH and 42CrMo4 is the commonly used MIM materials, the strengh and the corrosion performance have already verified by the locks manufacturers.